Moritz Stefaner of Well-formed data gives thought to propositional density as it pertains to visualization. There are two kinds. The first is surface propositions, which are straightforward statements about what we see. The second is deep propositions. These are statements that aren't so straightforward, like how we feel while looking at a graphic.
Moritz uses the FedEx logo as a simple example. First, the surface proposition:
“The FedEx logo type is purple” and “The FedEx logo type is set in a sans-serif font” are propositions, and because they describe salient, perceptible properties of the design, they are referred to as surface propositions.
Then there are deep propositions:
Now, the FedEx logo became famous for a perceptual trick: The white space between the E and the x cre ates an arrow. This arrow induces, by its semi otic read ing, a num ber of additional associations and readings of the design: “FedEx is on the go”, “FedEx is forward-thinking”, etc. Note that these propositions, unlike the surface propositions, are much harder to enumerate as they depend on the meaning that the observer ascribes to the arrow.
So how does this pertain to visualization? Oftentimes work is judged by graphical perception alone - how well does it show the trend or does it properly represent outliers? That's just the tip of the iceberg though. We have yet to look closely at what's underneath.
Read the rest on Well-formed data. It's interesting to think about, even if you disagree with the argument.